I've been using the RC version for a while now. Definitely uses less resources than Vista and its more easily tweeked to control what comes up on system start.
I also saw that MSDN will have it on the 6th. Seems, like I'll be doing some upgrades
I have a media center setup that really doesn't cut it under Vista. I'm looking forward to the upgrade. The 64 bit version will now support HD playback natively. I'm going to give that a shot and see how it works.
I'm also looking at Microsoft Security Essentials for virus protection. I'm trying to keep it as thin as possible.